I would just use the filter/pump you have as long as it is strong enough to pump the water to the top of the water fall. I use an external canister filter with a GS background and the return water comes back in at the top of my waterfall. I did not embed anything to do with the filter in the GS, not even the tubes as some people do, just incase I wanted to change something later. If you don't want to see tubes or anything you can hide them behind plants or cover them with silicone and then dirt or moss and make them look like a vine. Just some suggestions.